Design of a Knowledge Evaluation Questionnaire for Dental Specialists on Preservation and Extraction Indications of the First Permanent Molars

Statement of the Problem: The first permanent molar (FPM) teeth are the most important elements of mastication and are crucial in the improvement of functionally proper occlusion. However, in childhood, these teeth are most susceptible to caries. The loss of an FPM in a child can cause changes in the dental arches. These changes can occur throughout a person’s life. In such cases, the dentists and dental specialists need to decide whether to preserve or extract the FPM. Purpose: This study aimed to evaluate the extent of knowledge of dental specialists in Shiraz (Iran) on clinical guidelines for the preservation and extraction indications of FPMs. Materials and Method: The authors developed a dedicated questionnaire for the purpose of knowledge evaluation. A total of 6 orthodontists and 15 dental specialists, respectively confirmed the validity and reliability of the questionnaire. The 19-item questionnaire covered topics such as demographic data, preservation criteria for FPM teeth, and indications for FPM extraction. The survey was carried out across six dental disciplines in Shiraz (Iran) during July-August 2018. The data were analyzed using the SPSS software (version 22.0) with the dependent sample t test and one-way ANOVA. p Value< 0.05 was considered statistically significant. Results: Out of 89 dental specialists, 64 participants (53% male, 47% female) completed the questionnaire. The mean knowledge score for all participants was 10.09±3.93 (maximum of 19). The level of knowledge had a significant and inverse correlation with age (p< 0.001) and years of experience (p= 0.017). It also had a significant relationship with dental specialization (p< 0.001). Conclusion: The overall level of knowledge of the specialists was insufficient, except for the pedodontists and orthodontists. A re-education training program for dental specialists is strongly recommended.


Introduction
From the developmental and functional viewpoint, the first permanent molars (FPMs) are undoubtedly the most important teeth in a normal and balanced occlusion [1]. The importance of FPMs is regarded to their key role in preserving dento-facial harmony and masticatory function [2]. FPMs are the first permanent teeth to erupt in the oral cavity. However, due to their location in the dental arch, it is difficult to keep them clean. The long calcification period from birth to infancy and parents' Farrokhi F, et al. 21.87989.1305 10.30476/DENTJODS.20 21 unawareness of the time of eruption of the FPMs and of their importance in the dentition, contribute to the fact that FPMs are susceptible to dental caries [3]. According to previous studies, both the upper and lower FPMs are highly vulnerable teeth to dental caries and hypoplasia [4][5]. Dental caries can be prevented if appropriate fluoride therapy (in the form of toothpaste, varnish, and fissure sealant) based on the needs of the patients is applied [6]. Determination of a suitable treatment method for badly decayed and hypo-plastic FPMs requires consideration of various factors. For example, the severity of a toothache, the degree of pulp maturation, the extent of crown destruction, the status of the developing dentition, child's parents' attitude toward oral dental care, and the ability of the patient to tolerate a lengthy treatment under local anesthesia. Hence, some clinicians defend the early extraction of these teeth while others prefer to restore even an extensively decayed FPM [7]. anterior open bite malocclusion [8].

Questionnaire on Preservation and Extraction indications of the FPMs
The timing and overall approach to FPMs extraction should be tailored to different occlusal relationships [8].
Nevertheless, the ideal stage for the extraction of the FPM is at the age of 8-10 years [9]. According to the latest guideline, the best time to extract FPM is after the eruption of lateral incisor, but before the eruption of the second permanent molar and/or the second premolar [10]. When an FPM with poor prognosis is extracted during this period, it has been claimed to cause mesial movement of the permanent second molar into the FPM region and thus creating the most ideal contact relationship with the permanent second premolars [11]. On the other hand, studies have also shown that early loss of FPM might accelerate the development of the third molar on the extracted side compared to that of the contralateral teeth [12]. FPMs extraction might also create more space for the eruption of the third molar and its movement into a better position [13]. Additionally, cases involving the extraction of FPMs often result in com-prehensive orthodontic treatment; hence, determining the appropriate extraction timing can considerably facilitate and simplify the subsequent fixed orthodontic therapy [14]. However, FPMs extraction at an older age will lead to undesirable and insufficient space closure resulting in orthodontic malocclusion [11], in turn leading to contrary effects on the dental arch in both occlusion and function. These include reduced local function, tipping of adjacent teeth toward the extraction site, midline deviation, supra-eruption of opposing teeth, and unilateral chewing habit [3].
In their guideline, Cobourne et al. showed that enforced extraction of FPMs in children might be required. Therefore, it is important to determine the existence of any underlying malocclusion well before extraction. This guideline suggests that a compensating extraction (the extraction of the opposing tooth in the other arch) of an upper FPM is indicated after extraction of the lower FPM. However, routine compensating extraction of a lower FPM after the enforced extraction of the upper FPM is not recommended [10]. The balancing extraction (the extraction of the contralateral tooth in the same arch) of a sound FPM has been suggested to preserve the arch symmetry [10]. Currently, the balancing extraction of a sound FPM with the sole purpose of preserving the dental centerline is hardly justifiable [10].
Class-III malocclusions are often hard to manage; hence, balancing and compensating extractions are not indicated [10].
The present study aimed to evaluate the extent of knowledge of dental specialists in Shiraz (Iran) on clinical guidelines for the preservation and extraction indications of FPMs.

Materials and Method
The present cross-sectional study was carried out during July-August 2018 in Shiraz, Iran. Due to the unavailability of an appropriate data collection tool, a dedicated questionnaire was developed by the authors to evaluate the level of knowledge of dental specialists on clinical guidelines for the preservation and extraction indications of FPM. The content of the questionnaire was defined based on a review of various articles.
A list of dental specialists was obtained from the registry of Shiraz University of Medical Sciences (SUMS) from which 113 specialists practicing in Shiraz were identified. Subsequently, the survey was carried out among six dental disciplines, namely endodontics, pedodontics, prosthodontics, orthodontics, oral and maxillofacial surgery and restorative dentistry. The inclusion criteria were specialization in one of the abovementioned dental disciplines and place of practice in Shiraz. The exclusion criteria were general dental practitioners, incomplete questionnaire, and unwillingness to participate. Accordingly, from 113 identified specialists, 89 were recruited into the study.  Table 1). The knowledge score was determined by counting the total number of correct answers given by the participants. The scores ranged from 0 to 19; a higher score indicated better knowledge.

Validity and Reliability Tests
To confirm the validity of the knowledge evaluation qu- If you face a child presenting with a developing dentition affected by one or more first permanent molars of poor prognosis: 1-1 First permanent molars can be extracted and substitute with second permanent molar teeth with a proper treatment plan. If there are favorable conditions, balancing and compensating extraction of first permanent molars will be carried out to preserve the occlusal relationship and symmetric dental arch.

3
Which of the following statements have an impact on deciding for the balancing or compensating extraction of the first permanent molars? 3-1 The overall and the long-term prognosis of the first permanent molar * 3-2 The existence of second and third permanent molars The type of the present malocclusion *

4
If the enforced extraction of a lower first permanent molar is required, the compensating extraction of an upper first permanent molar should be recommended. It prevents over eruption of upper first permanent molar The compensating extraction of a lower first permanent molar has not been recommended when extraction of the upper first permanent molar is required.
Balancing extraction of a sound first permanent molar has been recommended to prevent midline deviation.
The timing for lower first permanent molar extraction is more important than the upper first permanent molar extraction timing. Because the migration of the lower second permanent molar is unpredictable.
The most favorable chronological age for enforced extraction of lower first permanent molar is 8-10 years, after the eruption of the lateral incisors but before the eruption of the second permanent molar and/or second premolar.
First permanent molar extraction before 8year is not suggested because of: 9-1 Absence of radiographic evidence of third permanent molar * 9-2 Second premolar migration to the space of extracted tooth * 9-3 Lingual drifting of anterior teeth and increased overbite *

10
Extraction of first permanent molars at the final stage of second permanent molar eruption or after it can cause: 10-1 Rotation and mesial tipping of second permanent molar to the space of the extracted tooth * 10-2 Distal tipping of the second premolar to the space of the extracted tooth * 10-3 Undesirable teeth contacts and occlusal relationship *

11
In class III cases if the enforced extraction of lower first permanent molar become needed the balancing and compensating extraction will be carried out.

12
First permanent molars have a key role in cheeks esthetic. Cheeks appear full and vibrant in the presence of first permanent molars.
estionnaire, the 19 items were initially reviewed by 6 orthodontists (academic staff) and based on their feedback initial modifications were implemented to shorten or clarify the questions. They unanimously agreed that the questions were appropriate for the targeted group.
Hence, the questionnaire was used without a question being modified or removed. To confirm the reliability of the knowledge evaluation questionnaire, the test-retest method was used. A total of 15 dental specialists (orthodontists (n=2), pedodontists (n=2), prosthodontists (n= 4), restorative dentists (n=3), endodontists (n=3), oral and maxillofacial surgeon (n=1)) were randomly selected to review the questions twice with an interval of 1 month. It is notable to say that these participants did not take part in the main study. The results from both tests were analyzed and the correlation coefficient was determined to confirm the reliability of the questionnaire.

Data Analysis
The data were analyzed using the SPSS software, version 22.0. Descriptive statistics such as mean and standard deviation, absolute frequency and relative frequency were determined. The Spearman non-parametric correlation test was used to investigate the relationship between knowledge, age and years of experience. The one-way ANOVA and dependent sample t test were used to compare the knowledge score with respect to the field of dental specialty as well as demographic characteristics. Additionally, the post-hoc Tukey's test was used to compare the extent of knowledge between the dental specialty groups. The data were presented as mean±SD and p< 0.05 was considered statistically significant.

Results
From 89 recruited dental specialists, 64 (71.9%) participants fully completed the knowledge evaluation questionnaire. The dental specializations of the participants are shown in Table 2.  Table 4).
The level of knowledge had a significant correlation with the type of dental specialization (p<0.001).
Amongst all dental specialists, pedodontists and endodontists had the highest [18] and the lowest [11] knowledge score, respectively ( Table 5). The post-hoc Tukey's test was used to determine the difference in knowledge scores among the six dental groups (Table 6).  The endodontists scored the lowest and their score significantly differed from all other disciplines, except for those of the oral and maxillofacial surgeons.
The percentage of dental specialists, per discipline, who agreed with each item of the questionnaire, is shown in Table 7. More than 80% of the pedodontists agreed with the rationale of at least 10 items of the questionnaire while more than 80% of the endodontists only agreed with the rationale of 1 item.

Discussion
The present study aimed to evaluate the extent of knowledge of dental specialists on clinical guidelines about  Cobourne et al. [10,15]  The level of knowledge among the dental specialists was ranked in the following descending order: pedodon-  In the case of a child with a developing dentition affected by one or more first permanent molars of poor prognosis:  for keeping arch symmetry [8,19]. Retrospective cohort studies have reported that the unilateral extraction of an FPM can be related to the development of both dental and skeletal arch asymmetries [1,20]. Evidence from other studies showed that the dental midline of any of the dental arches was not likely to be affected [21][22].

Questionnaire on Preservation and Extraction indications of the FPMs
Presently, it is difficult to defend the balancing extraction of a sound FPM solely for maintaining a dental midline.
The knowledge of the restorative dentists ranged from weak to very good. Nonetheless, they genuinely The results of the present study indicated that knowledge had a significant inverse correlation with age and years of working experience. Note that the majority of the participants were young and/or had less than 10 years of working experience; therefore, they were more interested in this topic than the senior specialists were.
Consequently, they obtained a higher score for the level of knowledge. The low score of senior specialists may be due to the lack of such guidelines while they were at dental school. On the other hand, their engagement with continued professional development such as courses and updated could have been insufficient. Female participants had a higher level of knowledge than their male counterparts did. Dental specialists graduated from SUMS performed better than those graduated from other Iranian universities did. Note that the sample size of those from other Iranian universities was low. Hence, the comparison was only made based on two groups of graduates. Consequently, the result cannot be interpreted as to conclude the educational protocol of SUMS is better than other Iranian universities. Moreover, dental specialists graduated during 2011-2016 (i.e. <5 years of experience) showed a higher level of knowledge.
The main strength of the present study is the fact that it is the first implementation and evaluation of the guideline. Hence, it can be considered as a benchmark for future studies. Since the study was conducted during the summer period, its main limitation was the unavailability of some specialists. As a direct result, the sample size in the present study was low. A nationwide study on the level of knowledge of the Iranian dentists is recommended to identify the shortcomings of the guideline. With some minor alterations, the designed questionnaire can also be used to evaluate the level of knowledge of general dentists. It is also recommended to design workshops on the importance of the guideline in order to enhance the level of knowledge of the specialists, particularly the endodontists, and the oral and maxillofacial surgeons.

Conclusion
The results of the present study showed that endodontists, prosthodontists, oral and maxillofacial surgeons, and restorative dentists had an insufficient level of knowledge on extraction indications of FPM with poor prognosis as well as its management in different types of malocclusions. Only the pedodontists and orthodontists demonstrated an adequate level of knowledge.
Considering the above, it is anticipated that general dentists would score even lower. Therefore, in support of fresh dental graduates, it is recommended that the dental curriculum include indications for FPM extraction.
Moreover, a re-education training program for dental specialists is strongly recommended.

Conflict of Interest
There is no competing interest to declare.